Residential buildings typically are fabricated by different trade groups along specific sequences. Thus, carpenters rough in walls, leaving exposed horizontally spaced vertical studs. Plumbers rough in water and drain piping, typically with vertical runs between adjacent studs and with capped end stubs projected several inches in front of the wall where a sink or water-using apparatus is to be mounted. This plumbing effort will commonly include the time-consuming fabrication from multiple elbows, pipes, end cap and tee components of an anti-knock compression assembly connected in each water line upstream of the end stub, for precluding hammer noises of water surging in the pipes as the sink valves are operated. Plasters then close the room side of the wall with wall panels or the like secured over the studs, fitting the capped pipe ends through openings cut in the wall to be exposed in the room. Carpenters will then install cabinets etc. as needed; and ultimately the sink will be installed proximate the stub ends, be it in the cabinet or free standing. The plumber will lastly finish connect the building pipe ends to the sink, by removing the end caps, connecting a stop angle valve on each open building pipe end, and running water and drain lines between the building valves and drain-outlet and the sink pipes and drain.
As each piping run between the adjacent wall studs extends approximately 2–8 foot upwardly from below the floor or downwardly from above the ceiling, it frequently is inadequately braced, making possible excessive pipe flexure as line or valve connections are initially made to the pipe or later removed and replaced by a new valve or the like.
Some alternative rough-in situations secure a box between and to adjacent studs that is open on one side toward the sink, with the vertical building pipe runs extending through openings in the box walls and terminating inside the box and being closed with an end cap or an angle stop valve connected thereto. The wall covering would not overlie the open box cavity, so that the pipe ends and/or valves remain exposed to the room interior. Finish connection can then be made between the sink lines and the exposed valves and drain. However, no anti-knock assembly piping would be used, or if used is in the box cavity to consume much of the overall box space (see U.S. Pat. No. 6,732,758 B2).
Should the stop angle valves be connected to the open water pipe stub ends during the plumbing rough in, instead of capping the pipe ends, the opening in the later added wall would have to be larger to fit over the valve, increasing clearance gaps around each pipe, which belie quality construction and might even could suggest potential access routes for insects or vermins between the wall and room interiors.